Electroconductive foams

Abstract

A lightweight, electroconductive foam comprising an effective amount of a conductive ionic salt, a polymer capable of complexing said conductive ionic salt and an effective amount of particulate conductive material such as carbon black or metal is disclosed. Additionally, a method of preparing a lightweight electroconductive foam having a surface resistivity less than about 10 10 ohms per square by an extrusion process is disclosed. Foams of the present invention exhibit relatively high conductivities yet require only relatively low amounts of particulate conductive material.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows. 
     
       1. A polymeric resin suitable for forming an electroconductive foam, said resin comprising: from about 0.5 percent to about 15 percent of a conductive ionic salt, said salt selected from the group consisting of sodium tetraphenylboron, lithium perfluoroalkane sulfonate, potassium perfluoralkyl sulfonate, sodium thiocyanate, sodium trifluoromethane sulfonate, lithium trifluoromethane sulfonate, and combinations thereof;   a polymer capable of complexing said conductive ionic salt., said polymer selected from the group consisting of a copolymer of ethylene and carbon monoxide, polyethers, polyesters, polyamides, polyurethanes, polyvinyl chlorides, polyaldehydes, and combinations thereof; and   an effective amount of particulate conductive material, said particulate conductive material selected from the group consisting of carbon black, finely divided metal particles, and combinations thereof, wherein said effective amount of said particulate conductive material is such that a foam formed from said resin is sufficiently electrically conductive to dissipate static electricity.   
     
     
       2. A polymeric resin in accordance with claim 1 wherein said polymer is a copolymer of ethylene and carbon monoxide. 
     
     
       3. A polymeric resin in accordance with claim 2 wherein said copolymer of ethylene and carbon monoxide has from about 1 to about 45 mole percent of CO units. 
     
     
       4. A polymeric resin in accordance with claim 3 wherein said copolymer of ethylene and carbon monoxide has from about 10 to about 20 mole percent of CO units. 
     
     
       5. A polymeric resin in accordance with claim 1 wherein said particulate conductive material is carbon black and is present in said resin in an amount of from about 5 percent to about 10 percent by weight. 
     
     
       6. A polymeric resin in accordance with claim 1 wherein said ionic salt has a concentration of from about 6 percent to about 10 percent. 
     
     
       7. A polymeric resin in accordance with claim 6 wherein said ionic salt is sodium tetraphenylboron. 
     
     
       8. A polymeric resin in accordance with claim 1 wherein said ionic salt is sodium tetraphenylboron. 
     
     
       9. A polymeric resin in accordance with claim 8 wherein said ionic salt is present in said resin in an amount of from about 0.5 to about 10 percent by weight. 
     
     
       10. A polymeric resin in accordance with claim 1 wherein said polymer is a copolymer of ethylene and carbon monoxide, said copolymer has from about 1 to about 45 mole percent CO units, and said ionic salt is sodium tetraphenylboron. 
     
     
       11. A polymeric resin in accordance with claim 1 wherein said resin has an overall melt index of from about 0.5 to about 5.0. 
     
     
       12. A polymeric resin in accordance with claim 11 wherein said resin has an overall melt index of from about 1.0 to about 3.0. 
     
     
       13. A lightweight electroconductive foam comprising: from about 0.5 percent to about 15 percent of a conductive ionic salt, said salt selected from the group consisting of sodium tetraphenylboron, lithium perfluoroalkane sulfonate, potassium perfluoralkyl sulfonate, sodium thiocyanate, sodium trifluoromethane sulfonate, lithium trifluoromethane sulfonate, and combinations thereof;   a polymer capable of complexing said conductive ionic salt, said polymer selected from the group consisting of a copolymer of ethylene and carbon monoxide, polyethers, polyesters, polyamides, polyurethanes, polyvinyl chlorides, polyaldehydes, and combinations thereof; and   an effective amount of particulate conductive material, said particulate conductive material selected from the group consisting of carbon black, finely divided metal particles, and combinations thereof, wherein said effective amount of said particulate conductive material is such that said foam is sufficiently electrically conductive to dissipate static electricity.   
     
     
       14. A lightweight electroconductive foam in accordance with claim 13 wherein said polymer is a copolymer of ethylene and carbon monoxide. 
     
     
       15. A lightweight electroconductive foam in accordance with claim 14 wherein said copolymer of ethylene and carbon monoxide has from about 1 to about 45 mole percent of CO units. 
     
     
       16. A lightweight electroconductive foam in accordance with claim 15 wherein said copolymer of ethylene and carbon monoxide has from about 10 to about 20 mole percent of CO units. 
     
     
       17. A lightweight electroconductive foam in accordance with claim 13 wherein said particulate conductive material is conductive carbon black. 
     
     
       18. A lightweight electroconductive foam in accordance with claim 13 wherein said ionic salt has a concentration of from about 6 percent to about 10 percent. 
     
     
       19. A lightweight electroconductive foam in accordance with claim 18 wherein said ionic salt is sodium tetraphenylboron. 
     
     
       20. A lightweight electroconductive foam in accordance with claim 13 wherein said ionic salt is sodium tetraphenylboron. 
     
     
       21. A lightweight electroconductive foam in accordance with claim 20 wherein said ionic salt is present in said foam in an amount of from about 0.5 to about 10 percent by weight. 
     
     
       22. A lightweight electroconductive foam in accordance with claim 13 wherein said foam has a density of from about 0.6 pcf to about 12.0 pcf. 
     
     
       23. A lightweight electroconductive foam in accordance with claim 13 wherein said foam has a surface resistivity of less than about 10 10  ohms per square.